Silencer duct with self-supporting acoustic absorbing member

ABSTRACT

A silencer duct includes at least one element including a three-dimensional (3D) chamber having a portion that is at least one of non-vertical or non-linear. An acoustic absorbing member is self-supporting such that is may be positioned within the portion to substantially fill the portion, but does not sag or droop over time.

BACKGROUND OF THE INVENTION

The disclosure relates generally to acoustic attenuation, and moreparticularly, to a silencer duct having an element having a non-verticalor non-linear elongated shape, and an acoustic absorbing material thathas the elongated shape. The acoustic absorbing material may be made ofa material being sufficiently rigid to maintain the shape duringoperation of the industrial machine in which the silencer element isemployed.

Noise reduction systems are used on a large variety of industrialmachines such as turbomachines to reduce the acoustic impact tosurrounding areas. In gas turbine systems, for example, noise reductionsystems may be employed in the turbomachine inlet duct, gas turbineenclosures and barrier walls. Traditionally, to attain the necessaryacoustic reduction requirements, silencer panels and acousticallytreated walls are used in the noisy areas. One mechanism to reduceacoustic impact is to treat walls with acoustic absorbing material.Another mechanism is to place silencer panels in areas where noisereduction is required, such as a working fluid flow path in an intakesystem duct to prevent noise escaping.

With regard to ducts, each duct typically includes a frame having anumber of silencer panels therein. Each panel typically includes anacoustic absorbing material such as mineral/glass wool positioned by ametal supporting member and surrounded by an enclosure includingstainless steel perforated sheets on the sides thereof. The sheets areheld together by stainless steel end caps. The stainless steelperforated sheets are typically welded to the supporting members thathold the acoustic absorbing material. The perforated stainless steelsheets hold the acoustic absorbing material intact with the supportingmembers and propagate the sound waves through the perforations into theacoustic absorbing material. The ducts are also typically made of ametal, such as steel or stainless steel. Use of steel for the ducts andsilencer panel enclosures presents a number of challenges. For example,the enclosures are very heavy, and are also difficult and costly tomanufacture due to the cost of the material and the need for welding toform the ducts and panels. In addition, the panels must be welded inplace to the surrounding metal duct and must be custom fit for aparticular sized duct. The frames created with the silencer panels arealso typically very large in relative size, and in particular, length.

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the disclosure provides a silencer duct, comprising:at least one element including a three-dimensional (3D) chamber having aportion that is at least one of non-vertical or non-linear; and anacoustic absorbing member positioned within the portion, the acousticabsorbing member substantially filling the portion and beingself-supporting.

A second aspect of the disclosure provides a turbomachine inlet,comprising: an intake frame forming a working fluid flow, the intakeframe operatively coupled to a compressor; and a silencer ductpositioned within the intake frame, the silencer duct including: atleast one element including a three-dimensional chamber having a portionthat is at least one of non-vertical or non-linear; and an acousticabsorbing member positioned within the portion, the acoustic absorbingmember substantially filling the portion and being self-supporting.

The illustrative aspects of the present disclosure are designed to solvethe problems herein described and/or other problems not discussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the disclosure taken in conjunction with the accompanyingdrawings that depict various embodiments of the disclosure, in which:

FIG. 1 shows a schematic view of an illustrative industrial machineemploying a silencer duct according to embodiments of the disclosure.

FIG. 2 shows a perspective view of a silencer duct according toembodiments of the disclosure.

FIGS. 3 and 4 show radial cross-sectional views of alternativeembodiments of the silencer duct of FIG. 2.

FIG. 5 shows an axial cross-sectional view of an embodiments of thesilencer duct of FIG. 2.

FIG. 6 shows an axial cross-sectional view of an alternative embodimentsof the silencer duct according to embodiments of the disclosure.

FIG. 7 shows a perspective view of an alternative embodiments of thesilencer duct according to embodiments of the disclosure.

FIG. 8 shows a perspective view of a silencer duct according to anotherembodiment of the disclosure.

FIGS. 9 and 10 show radial cross-sectional views of alternativeembodiments of the silencer duct of FIG. 8.

FIGS. 11-13 show a side view of various embodiments of perforations forperforated walls of the silencer ducts according to embodiments of thedisclosure.

FIGS. 14-16 show various embodiments of an acoustic absorbing memberaccording to the disclosure.

FIG. 17 shows an alternative embodiment of an acoustic absorbing memberaccording to the disclosure.

It is noted that the drawings of the disclosure are not to scale. Thedrawings are intended to depict only typical aspects of the disclosure,and therefore should not be considered as limiting the scope of thedisclosure. In the drawings, like numbering represents like elementsbetween the drawings.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, the disclosure provides a silencer duct and aturbomachine inlet including the silencer duct. The silencer duct mayhave an element having a non-vertical or non-linear elongated shape, andan acoustic absorbing material that has the elongated shape. Theacoustic absorbing material may be made of a material having sufficientrigidity to maintain the elongated shape during operation of theindustrial machine in which the silencer element is employed.

Referring to the drawings, FIG. 1 depicts an illustrative industrialmachine in the form of a turbomachine 10 (e.g., simple cycle gas turbinepower generation systems) that may include, among other things, a gasturbine system 12. Gas turbine system 12 may combust liquid or gas fuel,such as natural gas and/or a hydrogen-rich synthetic gas, to generatehot combustion gases to drive gas turbine system 12. Gas turbine system12 includes an air intake section 16, a compressor 18, a combustorcomponent 20, and a turbine component 22. Turbine component 22 isdrivingly coupled to compressor 18 via a shaft 24. In operation, air(e.g., ambient air) enters gas turbine system 12 through a turbomachineinlet or air intake section 16 (indicated by arrow 26) and ispressurized in compressor component 18. Inlet 16 may include an intakeframe 17 for forming a working fluid flow therein. As illustrated,intake frame 17 is operatively coupled to compressor 18, which includesat least one stage including a plurality of compressor blades coupled toshaft 24. Rotation of shaft 24 causes a corresponding rotation of thecompressor blades, thereby drawing air into compressor 18 via inlet 16and compressing the air prior to entry into combustor component 20.

Combustor component 20 may include one or more combustors. Inembodiments, a plurality of combustors are disposed in combustorcomponent 20 at multiple circumferential positions in a generallycircular or annular configuration about shaft 24. As compressed airexits compressor component 18 and enters combustor component 20, thecompressed air is mixed with fuel for combustion within thecombustor(s). For example, the combustor(s) may include one or more fuelnozzles that are configured to inject a fuel-air mixture into thecombustor(s) in a suitable ratio for combustion, emissions control, fuelconsumption, power output, and so forth. Combustion of the fuel-airmixture generates hot pressurized exhaust gases, which may then beutilized to drive one or more turbine stages (each having a plurality ofturbine blades) within the turbine component 22.

In operation, the combustion gases flowing into and through turbinecomponent 22 flow against and between the turbine blades, therebydriving the turbine blades and, thus, shaft 24 into rotation. In turbinecomponent 22, the energy of the combustion gases is converted into work,some of which is used to drive compressor component 18 through rotatingshaft 24, with the remainder available for useful work to drive a loadsuch as, but not limited to, an electrical generator 28 for producingelectricity, and/or another turbine. It is emphasized that turbomachine10 is simply illustrative of one application in which a silencer paneland system according to embodiments of the invention may be employed. Asair flows through inlet 16, noise is created such that a silencer system100 in which a silencer duct 102 according to embodiments of theinvention is employed to reduce the noise.

Referring to FIGS. 2-7 and 8-10, embodiments of a silencer duct 102, 202according to the disclosure are illustrated. Silencer duct 102, 202 mayinclude a duct body 104, 204. In embodiments illustrated, each duct body104, 204 has a polygonal cross-section; however, such a cross-sectionmay not be necessary in all instances. As will be described, each ductbody 102, 202 has a length that is typically shorter than conventionalsilencer frames and/or panels. As illustrated in the example in FIGS.2-6, duct body 104 has a substantially square cross-section, and in theexample shown in FIGS. 8-10, duct body 204 has a substantially hexagonalcross-section. As used herein, unless otherwise explained,“substantially” indicates having the stated characteristic for the mostpart, but perhaps with some small variances, e.g., for structuralinterconnection to other parts, accommodating adjacent structure, easeof manufacture, etc. Other polygonal cross-sections may also be employedsuch as but not limited to: triangular, pentagonal, octagonal, etc. Manyparts of silencer duct 102, 202 made be made of a plastic, for example,polyvinyl chloride (PVC), polypropylene(PP), polypropylene co-polymer(PPC), polypropylene homo-polymer (PPH), polyethylene (PE), high densitypolyethylene (HDPE) or any other plastic capable of withstanding theenvironmental and operational characteristics of the particular frameand/or industrial machine in which the duct is employed. Silencer ductbody 102, 202 may be formed by any now known or later developed fashionsuch as: injection molding, extrusion, or coupling of a number of parts,e.g., using fasteners, welding, etc.

As also shown in FIGS. 2 and 8, silencer duct 102, 202 may also includea first perforated wall 110, 210 extending within duct body 104, 204 andsubstantially parallel (e.g., no more than 1-3° difference) to aninterior surface 112, 212, respectively, of the duct body. Collectively,duct body 104, 204 and first perforated wall 110, 210 create an outerelement of silencer duct 102, 202. A first acoustic absorbing material120, 220 may be positioned between duct body 104, 204 and firstperforated wall 110, 210, respectively. Further, as will be describedfurther herein, a silencer element 130, 230 may extend axially throughduct body 104, 204, respectively. Each silencer element 130, 230 mayextend an entirety or a portion of an axial length of duct body 104,204. Each silencer element 130, 230 may include a second perforated wall140, 240, respectively, having a second acoustic absorbing material 150,250, respectively, adjacent thereto. As will be described in greaterdetail herein, in one embodiment, where the shape of silencer duct 102allows, acoustic absorbing materials 120, 150, 220, 250 may include anynow known or later developed sound absorbing material such as but notlimited to at least one of: foam, mineral wool, rock wool andfiberglass. The foam may be reticulated, or otherwise called open cellfoam. First acoustic absorbing material 120, 220 may be identical ordifferent than second acoustic absorbing material 150, 250.

As shown in FIGS. 8-10, in one embodiment, first perforated wall 210 maytake the form of an elongated hexagonal body having slightly smallerdiameter compared to duct body 204. Here, a space 212 (FIG. 9) iscreated between duct body 204 and first perforated wall 210 in whichfirst acoustic absorbing material 220 is positioned. Similararrangements may be formed for duct bodies having differentcross-sectional shapes. As shown in FIG. 3, with regard to firstperforated wall 110 of duct body 104, in on embodiment, it may be formedin configured in a similar fashion as shown in FIGS. 8-10, i.e., as anelongated square body having slightly smaller diameter compared to ductbody 104. Other arrangements may also be possible as described elsewhereherein. Each first perforated wall 110, 210 may be made of the samematerials as duct body 104, 204, i.e., a plastic. In any event, firstperforated wall 110, 210 and may be made as a unitary piece, e.g., as aninjected molded or extruded part, or in parts coupled together, e.g., byfasteners and/or welds. In an alternative embodiment, wall 110, 210 maybe made of a metal, e.g., steel, stainless steel, aluminum, etc.

As shown in FIGS. 2, 5 and 6, in one embodiment, silencer duct 102 mayinclude a first, axially curved portion 158 curving from an upstream end160 to a downstream end 162 thereof such that all of a working fluidflow passing therethough impinges at least a portion of an interiorsurface thereof. That is, a working fluid, e.g., air, flowingtherethrough has no clear line of sight from end 160 to 162 and istherefore incapable of taking a linear path through silencer duct 130.In this fashion, all of a working fluid is exposed to acousticabsorption of first and/or second acoustic absorbing material 120, 150.In the embodiments shown, first portion 158 has been illustrated as anelongated S-shape; other shapes such as sinusoidal (e.g., 2 silencerducts 102 coupled together) for preventing a linear path are alsopossible and considered within the scope of the disclosure.

As shown in FIG. 6, in an optional embodiment, silencer duct 102 mayalso include a second, axially linear portion 164 extending from atleast one of downstream end 162 of first, axially curved portion 148 andupstream end 160 of first, axially curved portion 158. As shown, eachlinear portion 164 may include the same structure as the rest ofsilencer duct 102 (i.e., duct body, first partition wall, first acousticabsorbing material, silencer element, etc.) Alternatively, linearportion(s) 164 may be simplified. For example, linear portions 164 mayinclude just duct body 104 with no acoustic absorption, or just ductbody 104 with first perforated wall 110 and first acoustic absorbingmaterial 120 with silencer element 130 omitted, or one or more portionsof silencer element 130 omitted.

Referring to FIGS. 2-6 collectively, silencer element 130 may take theform of a septum that includes a plurality of partitioning portions 132partitioning duct body 104 into at least two chambers or chamber ducts134. In this embodiment, each partitioning portion 132 includes a pairof second perforated walls 140 having second acoustic absorbing material150 positioned therebetween. Silencer element 130 can be formed in alarge number of ways to form chambers 134 such that each of secondperforated walls 140 couples to first perforated wall 110 (or duct body104) in one of a number of ways. In one embodiment, shown in FIG. 3,first perforated wall 110 is in the form of a square cross-sectionedwall and silencer element 130 is “+shaped”, having parallel secondperforated walls 140 with second acoustic absorbing material 150therebetween. Here, silencer element 136 may be a separate elementmounted within first perforated wall 110, e.g., by welding or fasteners.Alternatively, as shown in FIG. 4, silencer element 130 may be formed asfour (4) square cross-sectioned chamber ducts 134 providing secondperforated walls 150 and segments of first perforated wall 110. That is,in this example, first perforated wall 110 is formed by segments ofpartitioning portions 132 that are parallel to duct body 104 and areperforated walls—see break in wall at circle C.

Silencer element 130 can also be formed in a number of other shapesand/or with different segments. For example, element 130 may include: aT-shaped portion with an additional segment forming four chamber ducts,or with one single wall forming two chamber ducts 134, or as an X-shapeforming four triangular chambers 134. Silencer element 130 can also beformed such that chambers 134 have other shapes and/or sizes. Forexample, element 130 may be formed with curved radially walls and/orchambers 134 can be made of uneven size. In addition, element 130 neednot be formed with axially planar walls. For example, as shown in FIG.7, a silencer element 330 may spiral within a linear duct body from anupstream end 360 to a downstream end 362 of duct body 104 such that allof a working fluid flow passing therethough impinges at least a portionof an interior surface thereof. Silencer element 130, 330 (FIG. 7),i.e., walls thereof, may be formed integrally with duct body 104 and/orfirst perforated wall 110, e.g., by injection molding, or may be mountedtherein as a separate element.

Referring to FIGS. 8-10, in another embodiment, silencer element 230 mayinclude second perforated wall 240 that has a hollow interior 242. Inthis case, second acoustic absorbing material 250 is positioned withinhollow interior 242. In one embodiment, shown in FIG. 9, at least onesupport rib 270 (two shown) may extend from at least one of duct body104 or first perforated wall 210 to support the second perforated wall.Support rib(s) 270 may be axially spaced elements or may be solidelements that divide the chamber into two chamber ducts 234 (see FIG.9). Alternatively, as shown in FIG. 10, silencer element 230 may besupported at an axial end thereof in any now known or later developedfashion such that only one chamber 234 extends between first perforatedwall 210 and second perforated wall 140. In the example shown, secondperforated wall 240 has a substantially circular shape, i.e., creating acylindrical wall; however, wall 240 may take a variety of alternativeshapes such as hexagonal, square, etc.

Each second perforated wall 140, 240 may be made of the same materialsas duct body 104, 204, i.e., a plastic. In any event, second perforatedwall 140, 240 and may be made as a unitary piece, e.g., as an injectedmolded or extruded part, or in parts coupled together, e.g., byfasteners and/or welds. In an alternative embodiment, wall 140, 240 maybe made of a plastic or a metal; in the latter case, e.g., steel,stainless steel, aluminum, etc.

In any of the described embodiments, the various silencer elements 130,230, etc., may also optionally include an inner support 136, 236 toprovide additional support and/or additional separation of acousticabsorbing chambers. For example, as shown only in the embodiments ofFIG. 3, an inner support 136 may extend between pairs of secondperforated walls 150 of at least one of the partitioning portions 132 tosupport silencer element 130. Inner support 136 may be made of any ofthe materials listed for perforated walls 110, 140, and may be securedin any fashion, e.g., by connection to duct body 104 or, where possible,to first perforated wall 110. Alternatively, as shown in FIGS. 9 and 10,an inner support 236 may be axially positioned within hollow interior242. In one embodiment shown in FIG. 9, at least one of support ribs 270(both as shown) may couple to inner support 236 for supporting silencerelement 230. Inner support 236 may be made of any of the materialslisted for perforated walls 110, 140, vinyl or lead.

Referring to FIG. 11, first perforated walls 110, 210 and secondperforated walls 140, 240 each may include a planar sheet of material aslisted herein having perforations 180 therein to allow noise to beabsorbed by acoustic absorbing material 120, 150, 220, 250. As shown inFIG. 11, each perforation 180 may take the form of a hole extendingthrough the wall. Alternatively, as shown in FIGS. 12 and 13, eachperforation may include a different geometry of the openings (FIG. 12and FIG. 13). Other shapes such as diamond, triangular, rectangular,etc. may also be possible.

With further regard to acoustic absorbing material 120, 150, 220, 250,and with reference to FIGS. 14-17, due to the more complex shape ofsilencer duct 102, 202 compared to conventional vertical silencer panelspositioned in a frame, the aforementioned conventional acousticabsorbing materials may be insufficient in some applications. Inparticular, each silencer duct 102, 202 according to embodiments of thedisclosure include at least one element including a three-dimensional(3D) chamber 190, 290 (FIGS. 3 and 9 only) that has a portion that isnon-vertical or non-linear. As used herein, 3D chamber 190, 290 is anyspace in silencer ducts 102, 202 in which acoustic absorbing material120, 150, 220, 250 would be provided to absorb noise, and the portion of3D chamber 190, 290 may be part of the 3D chamber or may includesubstantially all of the 3D chamber, e.g., in one embodiment 90% or moreof the 3D chamber, or in another embodiment, 100% of the 3D chamber.Acoustic absorbing material 120, 150, 220, 250 substantially fills theportion, i.e., greater than 90% by volume. Ideally, acoustic absorbingmaterial 120, 150, 150, 250 continuously fills the majority of 3Dchamber 190, 290 during operation of the industrial machine, i.e., withno voids, cavities, emptiness or material disconnections. The elementhaving the portion of 3D chamber 190, 290 may take a variety of formssuch as any portion of the outer element formed by duct body 104, 204and first perforated wall 110, 210, or silencer element 130, 230 withsecond perforated wall 140, 240, or any other part of the a silencerduct having a non-vertical or non-linear configuration. That is, theportion is part of at least one of the outer element and the silencerelement. With regard to FIGS. 3-6, the portion may have an elongatedS-shape. In these situations, conventional acoustic absorbing materialssuch as mineral wool, rock wool or fiberglass, may not naturally takethe form of the three-dimensional chamber and, in any event, are notsufficiently rigid alone to persistently and substantially fill thethree-dimensional chamber, especially over a long duration of operationof the industrial machine. That is, the conventional materials may not,alone, provide sufficient rigidity to maintain or continually match/fillthe requisite portion of three-dimensional chamber, thus causingsagging, voids, etc., and consequently poor acoustic absorbingperformance. Such conditions may also lead to additional issues such asdamage caused by, for example, moisture absorption, high velocityworking fluid flow, etc. These situations may be harder to address whereat least part of at least one of the outer element and the silencerelement are made of plastic.

In an alternative embodiment according to embodiments of the disclosure,an acoustic absorbing member 192, 292 (FIGS. 3, 9, 12-15) is positionedwithin the portion of 3D chamber 190, 290 (FIGS. 3 and 9 only). Acousticabsorbing member 192, 292 substantially fills the portion. In oneembodiment, the portion may be filled greater than 90%, and in anotherembodiment, the portion may be filled 100% by volume. Furthermore, incontrast to where simply conventional acoustic absorbing materials areemployed, acoustic absorbing member 192, 292 is self-supporting. As usedherein, “self-supporting” indicates that member 192, 292, if removedfrom the portion of 3D chamber 190, 290 intact, would substantiallyretain its shape, i.e., with only minor divergence from its originalshape. In this fashion, acoustic absorbing member 192, 292 provides thenecessary acoustic absorbing characteristics required, but does not sagor droop over time. Ideally, although not necessary in all instances,acoustic absorbing member 192, 292 includes a material having isotropicacoustical properties, i.e., it absorbs acoustic energy in asubstantially uniform manner throughout. Acoustic absorbing member 192,292 may be positioned in the portion adjacent perforated wall thereof,e.g., 110, 210, 140, 240.

Acoustic absorbing member 192, 292 may take a variety of forms. In oneembodiment, shown in FIGS. 14-16, member 192, 292 may include at leastone of: a wire mesh, foam, fiber, and a gel, that is self-supporting,i.e., retains its shape. Member 192, 292 can have any shape matching theportion within 3D chamber 190, 290 which it is to substantially fill.Hence, it may have an elongated S-shape as in FIG. 14, be hexagonal orany part of a hexagon as shown in FIG. 15, substantially cylindrical orquarter round as shown in FIG. 16, etc. Where foam is employed, the foamcan be shaped to fit into the portion of 3D chamber during manufactureand then installed, or it may, alternative, include a spray foam, whichis applied in liquid form, expands and solidifies. That is, the acousticabsorbing material includes a spray application material that hardens inplace. The spray foam or spray application material may be open orclosed cell and may include, for example, pu, pur, polyurethane,polyisocyanurate or similar spray application materials that harden inplace. The spray foam may be applied during and/or after construction ofsilencer duct 102, 202.

In another embodiment, shown in FIG. 17, acoustic absorbing member 192,292 may include conventional materials such as at least one of mineralwool, rock wool and fiberglass, and a structural support 194 may beprovided for supporting the at least one of mineral wool, rock wool andfiberglass. Structural support 194 can take any form capable ofsupporting the wool(s) and/or fiberglass 196 in a collectivelyself-supporting fashion, e.g., a metal and/or plastic rigid orsemi-rigid element, etc. Ideally, structural support 194 is alsoacoustically permeable, e.g., of metal perforated plate or plasticperforated plate, or at the very least is structured to have limitedinterference with acoustical absorption of the surrounding acousticabsorbing material. In FIG. 17, structural support 194 is shown relativeto the FIGS. 3-6 embodiment; however, it is applicable to any of theembodiments disclosed. In FIG. 17, structural support 194 is positionedbetween layers of wool and/or fiberglass 196; however, it may bepositioned on just one side thereof. Structural support 194 and thewool(s) and/or fiberglass may be coupled in any fashion, e.g., using anadhesive, or mechanical fasteners. In an alternative embodiment, any ofthe acoustic absorbing materials, such as the wool(s) and/or fiberglass,may simply be adhered to duct body 104, 204 and/or perforated walls 110,210, 140, 240. Alternatively, an adhesive may be applied to internalsurfaces prior to application of any of the afore-mentioned materialsand embodiments to assist in holding the material's position.

While particular embodiments of the acoustic absorbing member have beendisclosed, other embodiments may also be employed. For example, theacoustic absorbing member may include materials applied in a certainorder, e.g., spray foam and then fiberglass, gel and then rock wool,etc., or may include any of various combinations of the listedmaterials, so long as the member presents in a self-supporting mannerthat does not allow droop, sag, etc., in final form.

Silencer duct 102, 202 provides a number of advantages over conventionalframe with silencer panel configurations. For example, the irregular andstreamlined flow paths created by polygon and/or S-shape geometries doesnot create much resistance to inlet air flow, but provides greaterimpact on the noise absorption, e.g., in a gas turbine during travelfrom compressor to outside, due to increased reactive impedance to theacoustical waves. As a result, silencer ducts according to embodimentsof the disclosure can be provided in a shorter length compared toconventional systems. Further, due to their plastic materials, thesilencer ducts have reduced weight and are easier to handle, havereduced cost, and are easier to fabricate using, e.g., injection moldingtechniques for at least part of the ducts. The ducts also eliminateextensive welding within conventional support panels and between supportpanels and supporting members. In addition, the plastic may provideslightly enhanced acoustic performance (e.g., a higher decibel (dB)attenuation of approximately, for example, 2 dB or above overallattenuation). In addition, plastic may allow increased perforation arealopening percentages compared to steel panels for the perforated walls.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A silencer duct, comprising: at least one elementincluding a three-dimensional (3D) chamber having a portion that is atleast one of non-vertical or non-linear; and an acoustic absorbingmember positioned within the portion, the acoustic absorbing membersubstantially filling the portion and being self-supporting.
 2. Thesilencer duct of claim 1, wherein the at least one element includes: anouter element including a duct body and a first perforated wallextending within the duct body and substantially parallel to an interiorsurface of the duct body; a silencer element extending axially throughthe outer element, the silencer element including a second perforatedwall, wherein the portion is part of at least one of the outer elementand the silencer element, and wherein the acoustic absorbing member ispositioned in the portion adjacent the perforated wall thereof.
 3. Thesilencer duct of claim 1, wherein the acoustic absorbing member includesat least one of: a wire mesh, foam, fiber, and a gel.
 4. The silencerduct of claim 3, wherein the foam includes a spray foam.
 5. The silencerduct of claim 1, wherein the acoustic absorbing member includes at leastone of mineral wool, rock wool and fiberglass, and a structural supportfor supporting the at least one of mineral wool, rock wool andfiberglass.
 6. The silencer duct of claim 5, wherein the structuralsupport is adhered to the at least one of the mineral wool, rock wooland fiberglass.
 7. The silencer duct of claim 1, wherein the acousticabsorbing member includes a spray application material that hardens inplace.
 8. The silencer duct of claim 1, wherein at least part of atleast one of the outer element and the silencer element are made ofplastic.
 9. The silencer duct of claim 1, wherein the portion has is anelongated S-shape.
 10. The silencer duct of claim 1, wherein the portionincludes substantially all of the 3D chamber.
 11. A turbomachine inlet,comprising: an intake frame forming a working fluid flow, the intakeframe operatively coupled to a compressor; and a silencer ductpositioned within the intake frame, the silencer duct including: atleast one element including a three-dimensional chamber having a portionthat is at least one of non-vertical or non-linear; and an acousticabsorbing member positioned within the portion, the acoustic absorbingmember substantially filling the portion and being self-supporting. 12.The turbomachine inlet of claim 11, wherein the at least one elementincludes: an outer element including a duct body and a first perforatedwall extending within the duct body and substantially parallel to aninterior surface of the duct body; a silencer element extending axiallythrough the outer element, the silencer element including a secondperforated wall, wherein the portion is part of at least one of theouter element and the silencer element, and wherein the acousticabsorbing member is positioned in the portion adjacent the perforatedwall thereof.
 13. The turbomachine inlet of claim 11, wherein theacoustic absorbing member includes at least one of: a wire mesh, foam,fiber, and a gel.
 14. The turbomachine inlet of claim 13, wherein thefoam includes a spray foam.
 15. The turbomachine inlet of claim 11,wherein the acoustic absorbing member includes at least one of mineralwool, rock wool and fiberglass, and a structural support for supportingthe at least one of mineral wool, rock wool and fiberglass.
 16. Theturbomachine inlet of claim 15, wherein the structural support isadhered to the at least one of the mineral wool, rock wool andfiberglass.
 17. The turbomachine inlet of claim 11, wherein the acousticabsorbing member includes a spray application material that hardens inplace.
 18. The turbomachine inlet of claim 11, wherein at least part ofat least one of the outer element and the silencer element are made ofplastic.
 19. The turbomachine inlet of claim 11, wherein the portion hasis an elongated S-shape.
 20. The turbomachine inlet of claim 11, whereinthe portion includes substantially all of the 3D chamber.